Turbofan engines, such as those used in commercial aircraft, include a fan driven by a shaft. The fan draws air into a compressor portion and a bypass duct. The compressor portion compresses the air and provides the compressed air to a combustor. The air is mixed with fuel and combusted within the combustor. The resultant combustion gasses are expelled from the combustor into a turbine, and expand through the turbine driving the turbine to rotate. At least a portion of the turbine is connected with the shaft and provides rotational force driving the fan to rotate. The air drawn into the bypass duct bypasses the compressor, combustor, and turbine and is expelled from the bypass duct at a bypass duct convergent-divergent exit nozzle.